Thawing of massive ground ice in mega slumps drives increases in stream sediment and solute flux across a range of watershed scales
Tóm tắt
Ice‐cored permafrost landscapes are highly sensitive to disturbance and have the potential to undergo dramatic geomorphic transformations in response to climate change. The acceleration of thermokarst activity in the lower Mackenzie and Peel River watersheds of northwestern Canada has led to the development of large permafrost thaw slumps and caused major impacts to fluvial systems. Individual “mega slumps” have thawed up to 106 m3of ice‐rich permafrost. The widespread development of these large thaw slumps (up to 40 ha area with headwalls of up to 25 m height) and associated debris flows drive distinct patterns of stream sediment and solute flux that are evident across a range of watershed scales. Suspended sediment and solute concentrations in impacted streams were several orders of magnitude greater than in unaffected streams. In summer, slump impacted streams displayed diurnal fluctuations in water levels and solute and sediment flux driven entirely by ground‐ice thaw. Turbidity in these streams varied diurnally by up to an order of magnitude and followed the patterns of net radiation and ground‐ice ablation in mega slumps. These diurnal patterns were discernible at the 103 km2 catchment scale, and regional disturbance inventories indicate that hundreds of watersheds are already influenced by slumping. The broad scale impacts of accelerated slumping are indicated by a significant increase in solute concentrations in the Peel River (70,000 km2). These observations illustrate the nature and magnitude of hydrogeomorphic changes that can be expected as glaciogenic landscapes underlain by massive ice adjust to a rapidly changing climate.
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Tài liệu tham khảo
Clesceri L. S., 1998, Standard Methods for the Examination of Water and Wastewater
Drever J. I., 2002, The Geochemistry of Natural Waters: Surface and Groundwater Environments
Ecosystem Classification Group(2010) Ecological Regions of the Northwest Territories—Cordillera Department of Environment and Natural Resources Government of the Northwest Territories Yellowknife NT Canada.
Environment Canada(2010) National Climate Data and Information Archive Fort McPherson NWT. [Available at http://climate.weatheroffice.gc.ca].
Environment Canada(2011) Water Quality Status and Trends of Nutrients in Major Drainage Areas of Canada Environment Canada Gatineau Que. Canada.
Environment Canada(2012a) Environment Canada Water Quality Monitoring Data Environment Canada Gatineau Que. Canada.
Environment Canada(2012b) Hydat Discharge Data for the Peel River Environment Canada Gatineau Que. Canada.
Environment Canada(2012c) NAtChem[Available atwww.on.ec.gc.ca/natchem/].
Frey K. E., 2007, Geochemistry of west Siberian streams and their potential response to permafrost degradation, Water Resour. Res., 43
Lamoureux S. F., 2009, Fluvial impact of extensive active layer detachments, Cape Bounty, Melville Island, Canada, Arct. Antarct. Alp. Res., 4, 59, 10.1657/1523-0430-41.1.59
Larsen S.andJ.Ormerod(2009) Low‐level effects of inert sediments on temperate stream invertebrates.Freshwater Biol. Applied issue 1–11 doi:10.1111/j.1365-2427.2009.02282
McCart P. J., 1980, A Review of the Systematics and Ecology of Arctic Char, Salvelinus alpinus, in the Western Arctic
Norris D. K.(1984) Geology of the northern Yukon and northwestern District of Mackenzie Map 1581A Geol. Surv. of Can. scale 1:500 000.
Rampton V. N., 1988, Quaternary Geology of the Tuktoyaktuk Coastlands, Northwest Territories, Memoir 423, 10.4095/126937
R Development Core Team. (2006) R: A Language and Environment for Statistical Computing Reference Index version 2.6.2.R Foundation for Statistical Computing Vienna Austria. [Available athttp://www.R‐project.org].
Romanenko F. A.(1998) Ground ice and relief evolution on the Islands and Coasts of the Russian Arctic inPermfrost – Seventh International Conference pp. 955–959 Collection Nordicana Yellowknife NT Canada.
Shur Y., 2005, The transient layer: Implications for geocryology and climate change science, Permafrost Periglac. Processes, 16, 5, 10.1002/ppp.518
St‐Onge D. A., 1999, The Bluenose Lake Moraine, a moraine with a glacier core, Geogr. Phys. Quat., 53, 287